Generating student pass/fail average based on 4-point rubric

Thanks in advance for any helpful advice. I am an elementary teacher, and we use a four-point rubric to score math tests. For example, a 1 indicates Below Basic, 2 Basic, 3 Proficient, and 4 Advanced. A score of 3 or 4 is considered passing, and I use a spreadsheet to track trends for each math standard that I teach. What I'd like to do is instruct Excel to treat a value of 3 or 4 as a passing grade, and generate a passing percentage at the bottom of a range of cells. That is, if 18 of the 24 grades in the cell range are a 3 or 4, Excel will treat them as passing and return a value of 75% (in this case). Is this possible? Thanks!